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Six airworthy orbiters have been built; the first, Enterprise (OV-101), was not built for orbital space flight, and was used only for testing glide and landing. Five space-worthy orbiters were built: Columbia (OV-102), Challenger (OV-099), Discovery (OV-103), Atlantis (OV-104), and Endeavour (OV-105). Enterprise was originally intended to be made fully space-worthy after use for the approach and landing test (ALT) program, but it was found more economical to upgrade the structural test article STA-099 into orbiter Challenger (OV-099). Challenger disintegrated 73 seconds after launch in 1986, and Endeavour was built as a replacement for Challenger from structural spare components.

NASA's current plans call for the Space Shuttle to be retired from service in 2011, after 30 years of service. Under the current plans, Discovery will be the first of NASA's three remaining operational Space Shuttles to be retired as the program winds down. Michael Suffredini of the ISS program has said that one additional trip will be needed in 2011 to deliver parts to the International Space Station. The Space Shuttle was originally to be retired in late 2010, but has been extended until June 2011 according to the NASA launch and mission schedule.

The three remaining space-worthy orbiters are planned to be transferred to education institutions or museums at the conclusion of the space shuttle program. Each museum or institution is responsible for covering the $28.8 million cost of preparing and transporting each vehicle for display. Enterprise is currently located at the Smithsonian Institution's National Air and Space Museum in the Udvar Hazy Center. Twenty museums have submitted proposals for displaying one of the retired orbiters including NASA visitors centers as well as aviation and science museums around the country. NASA is also making Space Shuttle thermal protection system tiles available to schools and universities. About 7,000 tiles are available on a first-come, first-served basis, but limited to one each per institution.